Emittance growth for the LHC beams due to head-on beam-beam interaction and ground motion.

The influence of ground motion on the LHC beam is estimated applying theexisting theories of particle diffusion due to a weak-strong beam-beamcollision with random offset at the interaction point. Noise at oddharmonics of the betatron frequency contributes significantlyto particle diffusion. The spectrum of the randomoffset, as obtained from the ground motion spectrum at the LHC site, showsa fast fall-off with frequency and the amplitude is very small even at the first harmonic. We find that the head-on beam-beam force inthe weak-strong approximation and ground motion by themselvesdo not induce significant diffusion over the lifetime of the beam.